The invention relates to a two-component cartridge, in particular a cartridge for discharging components of adhesives or foamed materials which are intended to get in contact with each other not before having been discharged, for the purpose of being mixed such that they react on each other.
Numerous solutions are known for two-component cartridges where the two components are stored separately from each other and are discharged at the same time and mixed with each other. In this connection a distinction is generally made between a coaxial cartridge and a biaxial cartridge. In the case of a coaxial cartridge an inner container is coaxially arranged inside an outer container. For simultaneous discharge of the two components by means of a commercially available standard evacuating means destined for a one-component cartridge an additional evacuating tool is required which comprises an inner mandrel and an annular mandrel of great length. When such a coaxial cartridge is used in connection with a conventional evacuating tool, said cartridge may have only half the length of a common cartridge because of the length of the required evacuating tool. In the case of biaxial two-component cartridges two containers each having a separate piston are arranged side by side. Here, a complex evacuating tool is needed. This solution requires high evacuating forces.
From DE-OS 2 007 199 an evacuating device for liquid cosmetic products is known where the one component is contained in an inner container and the other component is contained in an outer container. The inner container is adapted to fold like an accordion and its rear end is fastened to a piston which is displaceably arranged in the outer container. When the piston is advanced, the component contained in the outer container is moved in forward direction and the component contained in the inner container is also discharged because of the reduced volume of the inner container. According to another solution the piston comprises an annular space in which a knife is disposed which cuts up the cylindrical wall of the inner container when the piston is advanced in order to provide space for further advancement of the piston.
From DE 29 39 116 A1 a two-component cartridge is known which comprises an outer container, an inner container coaxially arranged therein and configured as a bellows-type section, and a piston displaceably arranged in the outer container. The piston is provided with a recess whose bottom supports the inner container. For displacing the piston the inner container is folded and received by the recess of the piston. The inner container is configured as a bag which is closed at the rear end by the bottom of the bag.
It is an object of the invention to provide a two-component cartridge for flowable media, which is easy to fill with the two components being kept separate from each other, and allows residual discharge of the two components.
In the two-component cartridge according to the invention the inner container comprises at its rear end a filling opening which is open at first and is closed by the piston when the material has been filled in. The piston comprises a projection axially extending into the inner container, said projection forming a central piston breast. The function of the piston projection is, on the one hand, that its central piston breast ensures maximum residual discharge of the component in the inner container, and on the other hand, that it forms a mandrel for ordered accommodation of the inner container when the latter is folded.
The two-component cartridge according to the invention can be evacuated using a commercially available standard evacuating means destined for one-component cartridges.
Good filling capability of the cartridge results from the fact that prior to placement of the piston both the inner container and the outer container are open at the rear end such that the two materials can be pressed into the respective filling opening. The materials can be pressed in simultaneously or one after the other.
Preferably, the projection provided on the piston forms, together with a recess of the piston and/or together with a constricted portion of the outer container, an annular space which receives the folded inner container when the piston is in the advanced position. This promotes the ordered folding of the inner container, and consequently an extremely small amount of residue of the corresponding component remains in the container.
The two-component cartridge according to the invention offers the possibility to accommodate the hazardous component of the two component materials in the inner container since the latter offers a residual evacuation capability. When the cartridges have been emptied, there is no danger that persons get in contact with a residue of the hazardous component which has not yet reacted. In the case of conventional coaxial cartridges it is however possible that the container wall shows fissure-type leaky areas and resultant leakage and adhesion of residues. The annular space receiving the folded inner container also reduces the amount of residue and forces the inner container into the form provided for the compressed condition.
According to a preferred embodiment of the invention it is provided that the piston comprises two separate piston portions of which a first piston portion comprises the first piston breast and a second piston portion comprises the second piston breast, and that one of the piston portions has a supporting surface for supporting and advancing the other piston portion. This allows the two containers to be filled one after the other and the filled container to be closed by inserting the respective piston portion. This prevents the two components from unintentionally getting into contact with each other. During the evacuation process the pressure is directly exerted only on one of the piston portions, and this piston portion supports and advances the other piston portion.
Each piston portion may comprise a piston edge supported on the wall of the outer container. In this way each piston portion is individually centered in the outer container.
The inner container is preferably configured as a bellows-type section being corrugatedly folded. The inner container is self-supporting and dimensionally stable. It is plastically deformable. For these requirements a metal is suited, in particular aluminum or an aluminum alloy. Aluminum offers the advantage that it has good plastic deformation characteristics. It has turned out that a bellows-type section of thin-walled aluminum is excellently suited as inner container.